I don't know any Joneses, and if I did I wouldn't waste my time trying to keep up with them.

Not on pointless things like the price of my car, color of my lawn or size of my TV, at least. I do like to compete on the size of my belly though, in that mine is way smaller than those of my neighbors. Not many people prioritize fitness the way I do though. For many it seems like the years between high school and the half-century mark are peppered with work + more work + very little else.

And then the 50s hit, and you're inactive, overweight, eating garbage and anticipating the death spiral. But it doesn't have to be that way. You don't want it to be that way.

Let's do the doom-and-gloom part first. Inspirational-uplifting-happy-fun-time comes later.

The impending doom is that inactivity is a major health burden. The longer you stay glued to that couch, the greater the risk of heart disease, diabetes, osteoporosis and some cancers, according to Bill Kohl, a professor of epidemiology and kinesiology at the University of Texas at Austin. "Continued inactivity into the 60s and 70s results in balance insufficiencies and lack of strength," Kohl told me. "Daily living becomes much harder."

And prolonged sitting is one of the worst things you can do, according to a 2009 study by researchers at the Pennington Biomedical Research Center in Baton Rouge, La. Published in Medicine & Science in Sports & Exercise, it examined 17,013 people over 200,000 "person years" and found that even for physically active people, more sitting equals more heart attacks, more cancer, more death.

"It's never too late to start exercising," Kohl says. Interestingly, these are the exact words the original fitness guru Jack LaLanne oft-repeated before his death at age 96 last year. "We've learned even the oldest of the old can increase their muscle mass. Even at 90," Kohl said. There are increases in quality of life and longevity.

"There are few things that physical activity doesn't help in terms of health," reports Kohl. "It is remarkable for preventing falls and therefore risks of broken hips." The functional health benefits from becoming a regular exerciser are tremendous for aging populations.

But Kohl admits that after a lifetime of inactivity it's hard to get started.

"It crept up on me," says Charlene Casey a records manager in Los Angeles and mother of one grown child, talking about how she came to be 70 pounds overweight. "Exercise was never a priority. I worked so hard at my job. By the time I got home there was feeding the family and housework. Working out was never on my mind."

But once her daughter was grown, Charlene found there weren't any more excuses, except for one: "Being tired was something I really had to overcome, but I knew it was just in my head."

"Just getting started is the biggest barrier," Kohl told me. "But a little goes a long way." Kohl is a fan of just trying to spend less time sitting as a way to start.

In Charlene's case, she found motivation (and savings) through on online coupon for 10 boot-camp-style fitness classes, which she started last fall. However, after the sale-priced sessions were up, it got really expensive.

"I didn't want to have to pay for what was essentially a cheerleader," she said. "So I told my husband, who is 64 and retired, that he had to help me be motivated and we just started walking together." They started off easy, just a couple of miles. But with each passing month they went further and further, to the point that within a few months they found they were walking six miles each outing, three times a week. What's more, Charlene got some inexpensive dumbbells, exercise bands, medicine balls and an inflatable fitness ball, and set up a simple home gym. For instruction, she got everything from videos she found on YouTube.

"I lost 70 pounds in six months," she said.

Once she started exercising, Casey said eating healthier got a lot easier too. And it rubbed off: Her husband lost more than 30 pounds, and her daughter jumped on the bandwagon as well and lost more than 50.

And Casey's success with walking is classic. It's by far the most popular form of exercise on the planet, and imparts far more health benefits than people acknowledge. Brisk walking for 45 minutes three times a week offers tremendous brain-boosting benefits and prevents mental deterioration, studies show.

Making it social

Casey found success by doing precisely what Kohl recommends: She made it social.

"Never underestimate the power of social support," Kohl told me. "It's critical." The more of a situation you can create where people rely on you to be there, or will at least give you some grief if you don't show, the better.

"Walk down the block. Walk the dog. Walk with a group," Kohl said. "Look for ways to build activity into your day: Take the stairs; park farther away from your destination; get off one bus stop earlier … " (He suggests people suffering from joint issues consider cycling.)

And if you ended up feeling more spry because you're logging so many miles, there's no reason you can't start running. There are plenty of octogenarian marathoners out there. Last year a centenarian finished a marathon in Toronto.

And try tacking some resistance training on to your workouts.

In 2009, researchers from Indiana University and Boston University compiled information from 121 trials comprising 6,700 participants and found that progressive resistance training — where an effort is made to get stronger — results in dramatic quality of life improvements. Published by the Cochrane Library, the study found it made a variety of daily tasks, such as carrying groceries, bathing, getting out of a chair and climbing stairs became much easier.

Because you likely don't want to become a bodybuilder, lifting weights doesn't have to be fancy or expensive. Simple and small equipment can make for a home gym — just like Casey did. The Cochrane review suggested working with a health professional or exercise specialist, and so do I.

Try to find someone with a degree in exercise physiology to come to your home and teach you to use simple equipment. It probably won't take more than a few sessions. For those with health concerns, the American College of Sports Medicine has some specialized certifications for people with certain conditions, so look for that.

If you've got a spouse or a friend to lift with, make it a team effort. Not only can you save money, but you'll be more motivated as well.

Just remember: It is very possible that you are not yet in the best shape of your life. So start finding time to spend on yourself and reap the rewards.